Lets say it's Quarry from the Mac Foster bout, of whatever you consider to be his personal best. Same for Sullivan. What happens?
This one is very interesting given Quarry’s success against punchers, however Sullivan would likely be the most aggressive one he’d faced not to mention reportedly having abnormal speed for a man of his size, often times even maintaining such attributes when he was out of shape and scaling 240 lbs. In the end we can never know for sure, but I’d be curious to see how Sullivan would react to Quarry’s counter-oriented style which was designed to make fighters like John L. think twice about being so aggressive. Judging from the Kilrain fight, Sullivan wasn’t foreign to employing a counter-oriented game plan himself.
We come up against teh usual problems here. We know exactly what Quarry was, but we only have an educated guess what Sullivan was. Working out what happened at one of Sullivan's fights, is a bit like trying to work out what happened at one of Jack the Ripper's murder scenes. The evidence is all very ephemeral. The best you can do is work which scenarios were possible, and which were not, then try to decide which was the most probable.